Gearing with duplex floating toothed portions

ABSTRACT

A gearing with duplex floating toothed portions for transmission between either two parallel shafts or two intersecting shafts comprising two meshing gears( 12 ) and ( 14 ) one gears ( 14 ) having coaxially disposed toothed portions ( 16 ) and ( 18 ) interacting with component ( 20 ) by spiral joints ( 22 ) and ( 24 ) different characteristics and an arrangement limitative divided spiral motions of toothed portions (! 6 ) and ( 18 ) relatively component ( 20 ) by parting plane “A” and arresting device ( 26 ). Both toothed portions ( 16 ) and ( 18 ) of gear ( 14 ) and meshing gear ( 12 ) have mating teeth whereby both toothed portions ( 16 ) and ( 18 ) are coupled positively with component ( 20 ). Even distribution of applied force between toothed portions ( 16 ) and ( 18 ) or elimination of the free angular displacement of the gear ( 12 ) and ( 14 ) with respect to each other within backlash are provided by choice of characteristics of spiral joints ( 22 ) and ( 24 ).

BACKGROUND

[0001] 1. Field of Invention

[0002] This invention relates to gearing with a split gear having twotoothed portions.

[0003] 2. Description of Prior Art

[0004] In symmetrical double helical or herringbone type gears the toothmeshing errors cause the uneven distribution of applied load between thetwo toothed portions of the gear.

[0005] Accordingly, efforts have been made when designing double toothedhelical gears to eliminate or at least to reduce these disadvantages.For example, in U.S. Pat. No. 3,102,433 there is disclosed a gearmechanism wherein one gear is axially fixed. The other gear is a freemove axially along its shaft or axially together with its shaft. Eachgear comprises of two toothed portions. The teeth of the first toothedportion having the smaller inclination angle in one direction have thegreater normal pressure angle. The teeth of the second toothed portionhaving the greater inclination angle in the opposite direction have thesmaller normal pressure angle. The substantially greater part of appliedload is taken-up permanently by the toothed portion having the lesserhelix angle. This gearing is less sensitive to the variations ofload-distribution due to mesh errors than is the gearing of thesymmetrical herringbone type.

[0006] Such gearing having the toothed portions which are fixed to eachother, however, exhibits the following disadvantages:

[0007] (a) Effective face width is the same as a typical gearing. Forincreasing loading ability there is a need to increase a centerdistance. The weight of the gear assembly will increase too.

[0008] (b) The technological process of manufacture of the teeth of thegears is expensive.

[0009] (c) Presence of dynamic load on the gear teeth particularly forhigh-speed gearing.

[0010] For high-speed gearing unavoidable inaccuracies in the tooth meshdue to tolerance, as well as errors in manufacturing and assembly, leadto high-frequency periodic accelerations of the driven gear. Theseaccelerations result in the imposition of acceleration forces on themeshing teeth. Due to the presence of backlash between non-working toothflanks, the acceleration of the driven gear leads also to separation ofthe working teeth followed by a reengagement. As a result, impact loadimpose on the gear teeth. This phenomenon, known as free impact orhammering, results in high dynamic loading on the gear teeth withattendant noise generation and vibration occurring.

[0011] An example of anti-backlash gearings are presented in U.S. Pat.No. 4,612,816. Each gear has coaxially disposed first and second toothedportions. The teeth of the first toothed portion have a firstinclination angle. The teeth of the second toothed portion have a secondinclination angle. Preloading means urge of the floating gear againstthe fixed gear. The teeth of the first toothed portion of the floatinggear mesh with the teeth of the first toothed portion of the fixed gear.The teeth of the second toothed portion of the floating gear intermeshwith the teeth of second toothed portions of the fixed gear along theopposite tooth flanks with respect to each other.

[0012] Such gear assembly does, however, exhibiting certaindisadvantages:

[0013] (a) Preloading means have a large, complex design, and complexadjustment.

[0014] (b) Such gear assembly can be used only in non-reversible onestage gear set.

[0015] (c) Manufacture of the gear assembly is expensive.

OBJECTS AND ADVANTAGES

[0016] Basic objects and advantages this invention are:

[0017] (a) to provide even distribution of an applied load between thefloating toothed portions for increasing the loading ability of thegearing without increasing of a center distance. The weight of the gearassembly will increase insignificantly. Service life will stay the same.

[0018] (b) to provide smooth working of the gearing.

[0019] (c) to eliminate dynamic load on the gear teeth for high-speedreversible gearing without the use of toothed portions with differenthelix angles and the means for preloading.

[0020] Other objects and advantages are to enable the use of theinvention for gearing of any classification and in reversiblemulti-stage gear assembly.

DRAWING FIGURES

[0021] The invention will be more particularly described in thefollowing discussion of the preferred embodiments thereof for withreference to the accompanying drawing wherein.

[0022]FIG. 1 is an elevational view, partly in section, showing a gearhousing incorporating the inventive concept hereof for transmissionbetween parallel and intersecting shafts.

[0023]FIGS. 2 and 2A are the diagrammatic illustrations of theengagement of the teeth of the gears and of the contact in the threadjoints of the gear assembly 1 of FIG. 1. The thread joints have theopposite directions.

[0024]FIGS. 3 and 3A are the diagrammatic illustrations of theinterengagement of the teeth of the gears and of the contact in thethread joints of the gear assembly 1 of FIG. 1. The thread joints havethe same direction but different lead angles.

SUMMARY

[0025] In accordance with present invention a gearing with duplexfloating toothed portions comprises a plurality of meshing gears one ofwhich having coaxially disposed two floating toothed portionsinteracting with component by spiral joint and arrangement limitativedivided spiral motions of toothed portions relatively component.

Description—FIGS. 1 to 5

[0026]FIG. 1 shows the elevation view of a gear assembly 10 for thetransmission between two parallel shafts is comprised of meshingherringbone gears 12 and 14. The gears may be formed either as spur oras helix. Gear 12 is mounted fixedly to a shaft 32 by means well knownin the art. Gear 12 cut on separate blanks or may be cut on singleblank. Gear 14 is formed with coaxially disposed toothed portions 16 and18. The toothed portions mounted to a component 20 interact with it byspiral joints, for example, by the right-hand and left-hand ball doublethread joints 22 and 24. Component 20 is mounted to its shaft 34 bymeans well known in the art.

[0027] Gear 14 has an arrangement which limits the divided axial motionsof toothed portions 16 and 18. The oncoming motions of toothed portions16 and 18 are limited by contact between them along a parting plane “A”.The counter motions of toothed portions 16 and 18 are limited by anarresting device 26. Arresting device 26 consists of pins 28 andretaining rings 30. A mounting of pins 28 provides the spiral motions oftoothed portions 16 and 18. The spiral motions must continue till of anengagement of teeth 48 and 50 of gear 12 with teeth 52 and 54 of toothedportions 16 and 18, as illustrated in FIGS. 2 and 2A.

[0028] Shafts 32 and 34 are each rotatably supported along parallel axesby bearing 36 and 38 and 40 and 42 mounted in a housing 44 and a cover46 respectively.

[0029] As illustrated in FIGS. 2 and 2A the directions of the helixes ofteeth 52 and 54 and of thread joints 22 and 24 must be opposite for eachtoothed portions 16 and 18 respectively. It is necessary that each ofthe toothed portions make the spiral motion relatively of component 20.The spiral motions must continue till of the engagement of teeth 48 and50 of gear 12 with teeth 52 and 54 of toothed portions 16 and 18respectively.

[0030] As illustrated in FIG. 3 and FIG. 3A, toothed portions 16 and 18are mounted to component 20 by right-hand ball double thread joints 22and 24. These thread joints have the same direction but the differentlead angles λ₁ and λ₂ thereto λ₁>λ₂. Therefore the axial displacementper revolution of toothed portion 16 is more than the axial displacementof toothed portion 18. As a result, by the axial displacement toothedportion 16 pushes or pulls of portion 18. Teeth 50 of gear 12 will meshwith teeth 52 of gear 14. Teeth 50 of gear 12 will intermesh with teeth54 of gear 14 along the opposite tooth flanks.

[0031] These thread joints 22 and 24 are overhauling. The followingequation (a) shows that thread joint is overhauling: $\begin{matrix}{{{d_{m}\left( \frac{{f_{r}\pi \quad d_{m}} - L}{{\pi \quad d_{m}} + {f_{r}L}} \right)} + {f_{c}d_{c}}} < 0} & (a)\end{matrix}$

[0032] Where:

[0033] d_(m)—diameter of contact in thread joints

[0034] f_(r)—coefficient of rolling friction in the thread joints

[0035] f_(c)—coefficient of friction between the toothed portions

[0036] d_(c)—average diameter of contact between the toothed portions

[0037] L—lead of thread

d _(c)≈1.2d _(m)(b)

[0038] after substituting (b) into (a) and simplifying with little error$\begin{matrix}{{f_{f} + {1.2\quad f_{c}}} < \frac{L}{\pi \quad d_{m}}} & (c)\end{matrix}$

$\begin{matrix}{{{tg}\quad \lambda} = \frac{L}{\pi \quad d_{m}}} & (d)\end{matrix}$

[0039] where λ—lead angle

[0040] after substituting (d) into (c)

f _(r)+1.2f _(c) <tgλ(e)

[0041] In FIG. 2 and FIG. 2A, and FIG. 3, and FIG. 3A an arrow 56indicates of the direction of a rotation of gear 14. Arrows 58 and 60indicate of the directions of axial forces W₆₂ and W₆₄ An arrows 62 and64 indicate of the directions of the tangential forces Q₆₂ and Q₆₄. Theaxial force W is calculated accordingly to the following equation (f):$\begin{matrix}{W = {F_{n}d_{1}\frac{1}{\left\lbrack {{d_{m}\left( \frac{{f_{r}\pi \quad d_{m}} \pm {L\quad \cos \quad \alpha_{n}}}{{\pi \quad d_{m}\cos \quad \alpha_{n}} \mp {f_{r}L}} \right)} + {f_{c}d_{c}}} \right\rbrack}}} & (f)\end{matrix}$

[0042] where:

[0043] F_(n)—force normal to the teeth

[0044] d₁—diameter of pitch circle

[0045] α_(n)—thread angle

[0046] after simplifying with little error

cos α_(n)=1 $\begin{matrix}{W = {F_{n}d_{1}\frac{1}{\left\lbrack {{d_{m}\left( \frac{{f_{r}\pi \quad d_{m}} \pm L}{{\pi \quad d_{m}} \mp {f_{r}L}} \right)} + {f_{c}d_{c}}} \right\rbrack}}} & (g)\end{matrix}$

[0047] The tangential force Q is calculate accordingly to the followingequation (h) $\begin{matrix}{Q = {W\left( \frac{f_{r} \pm \frac{L}{\pi \quad d_{m}}}{1 \mp \frac{f_{r}L}{\pi \quad d_{m}}} \right)}} & (h)\end{matrix}$

[0048]FIG. 1, there is depicted shows a gear assembly 70 for thetransmission between two intersecting shafts 80 and 32, one of which isthe drive shaft and the other of which is the driven shaft. Gearassembly 70 is comprised of first and second meshing bevel gears 72 and74. Gear 72 is fixedly mounted to shafts 80. Gear 74 is formed ofcoaxially disposed spiral floating toothed portions 76 and 78. Toothedportions 76 and 78 mounted to shaft 32 interact with it by spiraljoints. Shaft 32 is the component of gear 74. The mounting and theoperation of the bevel gearing are the same as the gearing with theparallel shafts therefore I do not describe its mounting and operation.

Operation—FIGS. 1 to 5

[0049] Referring now to FIG. 2 wherein teeth 48 and 50 of gear 12 meshwith teeth 52 and 54 of toothed portions 16 and 18 of gear 14respectively. Arrow 56 indicates of the direction of the rotation ofgear 14 by the action of an applied force. As a result, axial forces W₅₈and W₆₀ and the tangential forces Q₆₂ and Q₆₄ are generated in threadjoints 22 and 24 at their contacting surfaces. The forces W₅₈ and W₆₀are the reason for contact between toothed portions 16 and 18 along theparting plane “A”. Forces Q₆₂ and Q₆₄ are the reason for the engagementof teeth 52 and 54 of toothed portions 16 and 18 with teeth 48 and 50 ofgear 12 respectively. The resultant of the forces W₅₈ and W₆₀ must beequal zero. The applied force distributes between toothed portions 16and 18 in proportion to the relationship between the tangents of thelead angles λ₁ and λ₂ of thread joints 22 and 24. Each toothed portions16 and 18 of gear 14 will be coupled positively with component 20 bythread joints 22 and 24.

[0050] Supposing teeth 52 or 54 one of toothed portions 16 or 18 do notengage with teeth 48 or 50 of gear 12 respectively. The toothed portionthe teeth of which mesh with the teeth of gear 12 has a conditional name“first toothed portion”. The toothed portion the teeth of which do notengage with the teeth of gear 12 has the conditional name “secondtoothed portion”. As a result, by the action of the applied force “firsttoothed portion” makes the spiral motion relatively of component 20. Atthe same time “first toothed portion” pushes “second toothed portion”which makes the spiral motion relatively component 20 too. The pushingforce is equal the axial force W and acts at the parting plane “A”. Thespiral motions of the toothed portions will continue till of theengagement of the teeth “second toothed portion” with the teeth of gear12. Now the gearing is working as illustrated in FIG. 2.

[0051] Referring now to FIG. 2A, wherein arrow 56indicates of thedirection of the rotation of gear 14 by the action of the applied force.All forces W₅₈ and W₆₀ and Q₆₂ and Q₆₄ have the opposite directionrelatively of forces W₅₈ and W₆₀ and Q₆₂ and Q₆₄ illustrated in FIG. 2.As a result, toothed portions 16 and 18 contact with retaining rings 30of arresting device 26 along their contacting surfaces. The operation ofthread joints 22 and 24 is the same as FIG. 2 therefore I do notdescribe it.

[0052] Referring now to FIG. 3 wherein teeth 48 of gear 12 mesh withteeth 52 of toothed portion 16. Teeth 50 of gear 12 intermesh wit teeth54 of toothed portion 18 along the opposite tooth flanks with respect toeach other. Free angular displacement of gears 12 and 14 within backlashare prevented and possibility of hammering is eliminated. Arrow 56indicates of the direction of the rotation of gears 14 by the action ofthe applied force. As a result, the axial forces W₅₈ and W₆₀ and thetangential forces Q₆₂ and Q₆₄ are generated in thread joints 22 and 24at their contacting surfaces. Forces W₅₈ and W₆₀ are the reason forcontact between toothed portions 16 and 18 along the parting plane “A”.Force Q₆₂ is the reason for the engagement of teeth 48 of gear 12 withteeth 52 of gear 14. Force Q₆₄ is reason for the interengagement ofteeth 50 of gear 12 with teeth 54 of gear 14 along the opposite toothflanks with respect to each other. The resultant of forces W₅₈ and W₆₀must be equal zero. The applied force distributes between toothedportions 16 and 18 in proportion to the relationship between thetangents of the lead angles λ₁ and λ₂ of thread joints 22 and 24. Eachtoothed portions 16 and 18 of gear 14 will be coupled positively withcomponent 20 by thread joints 22 and 24.

[0053] Supposing teeth 54 of toothed portion 18 do not interengage withteeth 50 of gear 12. As a result, by the action of the applied forcetoothed portion 16 makes the spiral motion relatively of component 20.At the same time it pushes toothed portion 18 which makes the spiralmotion relatively component 20 too. The pushing force is equal axialforce W and acts at the parting plane “A”. The spiral motions of toothedportion 16 and, consequently, of toothed portion 18 will continue tillof the interengagement of the teeth of toothed portion 18 with the teethof gear 12. Now the gearing is working as illustrate in FIG. 3.

[0054] Referring now to FIG. 3A, wherein arrow 56 indicates of thedirection of the rotation of gear 14 by the action of the applied force.All forces W₅₈ and W₆₀ and Q₆₂ and Q₆₄ have the opposite directionrelatively of forces W₅₈ and W₆₀ and Q₆₂ and Q₆₄ illustrated in FIG. 3.As a result, toothed portions 16 and 18 contact with retaining rings 30of arresting device 26 along their contacting surfaces. The operation ofthread joints 22 and 24 is the same as FIG. 3 therefore I do notdescribe it.

Conclusion, Ramification and Scope

[0055] Accordingly the reader will see that the gearing with duplexfloating toothed portions of this invention for the transmission can beused:

[0056] to provide even distribution of applied load between the toothedportions for increasing loading ability of a typical gearing withoutincreasing of a center distance, but with increasing of effective facewidth of the gears. The weight of the gear assembly will increaseinsignificantly. Service life of the gearing with increased load willstay the same.

[0057] to provide smooth working of the gearing

[0058] for high-speed gearing to eliminate dynamic loading on the gearteeth without the use of the toothed portions having different helixangles and preloading means.

[0059] Furthermore, such invention has the additional advantages inthat, it can be used in the reversible multi-stage transmission of anyspecification.

[0060] Although only a few exemplary above contains many specificitiesthese should not be construed as limiting the scope of the invention butas merely providing illustrations of some of the presently preferredembodiments of this invention. For example, the gear with the floatingtoothed portions can be used as an idler, can be coupled with its shaftby a coupling, the spiral joints and the arrangement can have otherdesign etc.

[0061] Thus the scope of the invention should be determined by theappended claims and their legal equivalents, rather than by examplesgiven.

I claim:
 1. A gearing with duplex floating toothed portions having aplurality of meshing gears, characterized by: a) one of said gears isprovided a component with two spiral sections of differentcharacteristics, b) said gear is provided coaxially disposed two toothedportions having spirals are supposed for interaction with the spiralsections of the component, c) an arrangement of said gear limitativedivided spiral motions of the toothed portions relatively of thecomponent, thereby each the toothed portions of said gear and at leastone of said meshing gear will have mating teeth, selected from the groupconsisting of engaging and interengaging teeth whereby each the toothedportions will be coupled positively with the component by spiral joints.